The present invention relates to mobile telecommunication systems. In particular, the invention is directed to a method of improving service level selection during a data transmission in a mobile communication network.
More specifically the invention relates to High Speed Circuit Switched Data (HSCSD) calls in GSM.
The Problem Area
During a non-transparent HSCSD call, the mobile station (MS) may (depending on negotiated parameters at call setup) request the network to add or remove one or more traffic channels used for the transmission (usually referred to a service level up and downgrading). This can be used to release channels during periods of the call when a small amount of data is transmitted through the mobile network, and to allocate more channels when the data flow increases.
In order to use this mechanism efficiently, the MS must know how much data is passing through the fixed network, see FIG. 1. Briefly put, if the data transmission rate in the fixed network is less than the total capacity of the allocated channels in the mobile network (i.e., the air interface user rate, AIUR), the MS should initiate a service level downgrading, if it is more, it should initiate an upgrading.
In order to know when to initiate up and downgrading, the MS must xe2x80x9cseexe2x80x9d beyond the mobile network; more specifically beyond the Interworking Function (IWF), see FIG. 1. In the current implementations of GSM, the MS can get an indication that the data rate in the fixed network is low compared to the AIUR. In the downlink direction, this is done by looking at the amount of data it receives and, in the uplink direction, through use of flow control. However, there are no similar indications that the data rate in the fixed network is high compared to the AIUR, meaning that the MS should initiate a service level upgrading.
Known Solutions
If the data transmission rate in the fixed network is constant and data are not compressed, the data transmission rate is known to the mobile user through the parameters negotiated at call setup. If data are compressed on the mobile leg only, the mobile user may examine the compression factor, which may vary.
If the data transmission rate in the fixed network is unpredictable, e.g., the fixed network is an IP network, the mobile user may guess when to upgrade. For instance, he may guess that an upgrade is useful immediately after starting to download a large file. He may also occasionally request an upgrade and, if that has no effect, request a subsequent downgrade.
Another solution is to let the IWF initiate the upgrading.
Problems with Known Solutions
Examining the compression factor may be intricate to implement.
Transmission of a large file does not necessarily mean that an upgrading will have any effect since the fixed network may be congested.
Upgrading and downgrading are relatively extensive and slow processes and unnecessary upgrades should be avoided. Depending on the operator""s charging policy, the user may have to pay extra for each channel in use. The problem with letting the network initiate the upgrading is that this may interfere with the user""s wishes. The user may want to control the upgrading more strictly due to, e.g., extra charges in connection with upgrading.
Further Prior Art
From WO 96/10305 (Nokia Telecommunications Oy) there is known a data transmission method in a time division multiple access mobile communication system. The mobile communication network can dynamically adjust the channel configuration assigned to the data call within the limits of a minimum and a maximum requirement, depending on the varying allocation level of the network resources. This functionality is, in relation to GSM standards, referred to as a minimum value of 1 and a maximum value determined by the BC-IE parameters mTCH (maximum number of TCH). In other words, such a network may initiate upgrading and downgrading, but is limited to the interval 1 through mTCH. Said standards also allow the user to change the mTCH parameter during a call, i.e., a so-called user initiated service level upgrading and downgrading.
However, this prior art does not give any instructions for giving a user terminal, and more specifically a mobile station, a xe2x80x9chintxe2x80x9d about increasing the value of said mTCH.
An object of the invention is thus to provide a method wherein the service level upgrading and downgrading can be affected in a far more effective and expedient manner, as compared with prior art.
Another object of the present invention is to provide a method for improving service level selection making it possible for the mobile user to allocate bandwidth in a more flexible way, especially for circuit switched data calls in a mobile network.
Still another object of the present invention is to provide a method wherein it is possible for the mobile user to allocate required bandwidth more dynamically, for thereby reducing costs involved therein.
Yet another object of the invention is to provide a method by which the upgrading and downgrading of number of traffic channels used can be made at any time during a call, and more selectively depending on the required transmission capacity.
Still another object of the present invention is to provide a method which can be used in an advantageous manner in network communication systems having a bursty traffic, for example in connection with internet and intranets.
Thus, in one aspect, the present invention is a method of improving service level selection in a communication system having a mobile network and a fixed network. An interworking function (IWF) is arranged between the fixed network and a mobile station (MS) operating in the mobile network, and High Speed Circuit Switched Data (HSCSD) services are provided to the MS utilizing at least one traffic channel in the mobile network. The method includes the steps of establishing a HSCSD session in which data is exchanged between the fixed network and the MS; and determining by the IWF whether a data rate in the fixed network differs significantly from an Air Interface User Rate (AIUR) in the mobile network. Upon determining that the data rate in the fixed network differs significantly from the AIUR, the IWF sends an indication to the MS recommending a change in service level selection. This is followed by sending a request from the MS to the mobile network to change the service level selection; and adding or removing traffic channels to the HSCSD session by the mobile network, in accordance with the request from the MS.
Generally, the solution according to the present invention is to let the Interworking Function (IWF) signal to the mobile user when an upgrade or downgrade may be useful.
Further features and advantages of the present invention, as well as the implementation thereof, will appear from the following description taken in conjunction with the appending drawings, as well as from the attached patent claims.